He later became a police detective in Chicago. He died on January 25, 1956, at the age of 52, after being shot and killed during an investigation.
He and his partner were at the Boulevard Hotel in Chicago during a narcotics investigation. They were arresting two wanted men and searching them for weapons when one pulled out a .38 caliberpistol and started firing, then fled. Kelliher was shot twice in the chest and his partner was hit in the hand. They were both rushed to the Illinois Research Hospital, where Kelliher later died of his wounds.[4][5]
